The Solar System's Most Spectacular Polar Superstorms

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The Solar System's Most Spectacular Polar Superstorms

A long-lasting megastorm in the atmosphere above Venus’ south pole is more chaotic and unpredictable than previously thought. This is the finding of a new study that looked at the planet's polar atmosphere in greater detail than ever before, which was published Mar. 24 in Nature Geoscience.
Venus has a dense carbon-dioxide atmosphere that creates a surface pressure more than 90 times stronger than Earth’s at sea level and temperatures greater than 450 degrees Celsius, hot enough to melt lead. Though the planet rotates very slowly — a day on Venus lasts 243 Earth-days — its atmosphere travels at speeds of 360 km/hr, whipping around the planet in just four Earth-days. Satellites have spotted an S-shaped vortex with two eyes near each of its poles.
A polar vortex is a gigantic persistent cyclone-like storm hovering high in the atmosphere over a planet’s antipodes. Almost every planet or moon with a substantial atmosphere has been shown capable of possessing one, including Earth. They interact with and shape the long-term climatological patterns of an atmosphere and, at least on our own world, are important in modeling climate change and ozone depletion.
Considering that Venus is not the only world with some crazy atmospheric dynamics, here we take a look at the solar system’s most incredible polar vortices.
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Chaotic Venus Vortices

Using the European Space Agency’s Venus Express satellite, astronomers looked at the Venusian south polar vortex very closely. The permanent cyclone is 20 km high, more than twice as tall as Mount Everest, and was found to wander around the pole chaotically. Scientists mapped two separate centers of rotation for the storm, each at a different altitude, that moved independently of one another with no particular pattern. This stands in contrast to polar vortices on other planets, like Earth, which are much more stable.
Image: The two independently changing shapes of Venus’ south polar vortex. Upper panels show day-to-day variations in the upper cloud layer at 63 km while lower panels show clouds at 42 km. ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Universidad del País Vasco (I. Garate-Lopez)

Saturn's Terrifying Eye

Saturn has possibly the craziest polar storm in the solar system. Seen here is a terrifying close-up of the eye of the cyclone that persists at its North Pole, taken with NASA’s Cassini spacecraft.
Image: NASA/JPL-Caltech/SSI

Hexagon on Saturn

One of the most insane things about Saturn’s north polar vortex is its bizarre shape: It looks like an almost perfect hexagon. The strange shape — seen here in infrared wavelengths from the Cassini spacecraft — wraps around the planet at near 78 degrees northern latitude. Each side of the hexagon is 13,800 km long, a bit bigger than the Earth’s diameter. Saturn’s South Pole also has a vortex, though it is not shaped like a hexagon. Below is a short animation of the polar vortex spinning.
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Image: NASA/JPL/University of ArizonaVideo: NASA/JPL/Space Science Institute

Earth's Poles

Earth has two polar vortices, located over the Arctic and Antarctic, and circling through our planet’s troposphere and stratosphere. The polar vortex is strongest in winter, allowing the prevailing westerly winds to flow fiercely. In the Arctic, the vortex is centered over northeast Siberia in Russia and Baffin Island off the coast of Canada.
Around Antarctica, the polar vortex is much more stable than in the north and hovers around the edge of the Ross Ice Shelf. Nitric acid in the south polar clouds interact with CFCs, which depletes ozone and is partially responsible for the ozone hole.
Image: 1) Sea-level pressure in 2010 corresponding to the approximate centers of the north polar vortex. National Snow and Ice Data Center courtesy NOAA/ESRL PSD 2) Changes in weather patterns through fall and winter and interactions with the north polar vortex. Nicolle Rager Fuller, National Science Foundation

Small Vortex on Mars

Though Mars has a very thin atmosphere, it can still support a polar vortex such as the one discovered here with Hubble in 1999. The storm hovers near the planet’s North Pole and is more than 1,600 km across. The vortex seen then was relatively dust free and therefore probably consisted of water vapor clouds.
Image: NASA/JPL/STScI

Tiny Titan Vortex

Even some of the moons in our solar system can support polar vortices. Seen here is Saturn’s biggest moon, Titan, with a mass of swirling atmosphere spinning around its south pole. The vortex formed in 2009, with the coming of Titan’s southern winter. An animation below shows the vortex’s motion.
Image and animation: NASA/JPL-Caltech/Space Science Institute